Smith's butterflyfish

Lore & Background

Smith's butterflyfish has the anterior half of the body and associated fins dark brown, while the posterior half and fins are yellow. The posterior soft rayed part of the dorsal fin and the anal fin have blue margins. The separation of the two colour blocs on the body is irregular, and the spines of the dorsal fin are also yellow over the brown anterior part of the body. It attains a maximum total length of 18 centimetres (7.1 in), though the article also states 19 centimetres (7.5 in).

This species was described in 1975 by the American ichthyologist John Ernest Randall, with the type locality given as off Young's Rock, Pitcairn Island. The type specimens were collected by the ichthyologist C. Lavett Smith, Jr. of the American Museum of Natural History, whom Randall honoured with its specific name.

Smith's butterflyfish occurs on rocky reefs with dense growth of algae and at least a little coral. It is often encountered in large aggregations in the middle of the water column where they feed on zooplankton. This oviparous species forms pairs for breeding.

Reader's Guide

Smith's butterflyfish is significant primarily for its extreme endemism, being recorded only from the British Overseas Territory of Pitcairn Island, Rapa Iti and Marotiri in French Polynesia, with a single confirmed record from Easter Island. This restricted distribution makes it a species of interest for biogeography and conservation. The species appears in the aquarium trade but is extremely rare in that trade, and it is on display at the Waikiki Aquarium. Its description in 1975 by John Ernest Randall, honoring C. Lavett Smith, Jr., ties it to a specific scientific legacy. The fish's distinctive two-tone coloration—dark brown anterior and yellow posterior with blue margins on the dorsal and anal fins—makes it visually notable. Its habit of forming large aggregations in the water column to feed on zooplankton, and its oviparous breeding in pairs, provide insight into its ecological role on rocky reefs with algae and some coral.

Did You Know?

• Smith's butterflyfish is endemic to the south western Pacific Ocean, recorded only from Pitcairn Island, Rapa Iti, Marotiri, and one confirmed record from Easter Island.
• It attains a maximum total length of 18 to 19 centimetres (7.1–7.5 in).
• The species was described in 1975 by John Ernest Randall, who named it after C. Lavett Smith, Jr., who collected the type specimens.
• It is extremely rare in the aquarium trade but is on display at the Waikiki Aquarium.